Light Distribution in 3D-Printed Thermoplastics

Daylight distribution is an essential performance parameter for building facades that aim to maximize user comfort while maintaining energy efficiency. This study investigates the feasibility of using 3D-printed thermoplastic to improve daylight distribution and transmission. To identify how geometry influences light distribution and transmission, 12 samples with various patterns were robotically fabricated. In a physical simulation of spring, summer, and winter, a robotic arm was used to direct light onto the samples in both the vertical and horizontal print pattern directions. In addition, three samples of conventional facade materials, including a polycarbonate panel, a polycarbonate sheet, and a single sheet of glass, were compared with the 3D-printed samples. All samples were examined and compared using high dynamic range imaging to qualitatively characterize luminance. The data analysis demonstrated that 3D-printed geometry can successfully generate customizable diffusive light distribution based on the needs of the user. Furthermore, the results showed that the vertical pattern direction had higher light transmission values than the horizontal pattern direction.

A framework for robotic excavation and dry stone construction using on-site materials

Automated building processes that enable efficient in situ resource utilization can facilitate construction in remote locations while simultaneously offering a carbon-reducing alternative to commonplace building practices. Toward these ends, we present a robotic construction pipeline that is capable of planning and building freeform stone walls and landscapes from highly heterogeneous local materials using a robotic excavator equipped with a shovel and gripper. Our system learns from real and simulated data to facilitate the online detection and segmentation of stone instances in spatial maps, enabling robotic grasping and textured 3D scanning of individual stones and rubble elements. Given a limited inventory of these digitized stones, our geometric planning algorithm uses a combination of constrained registration and signed-distance-field classification to determine how these should be positioned toward the formation of stable and explicitly shaped structures. We present a holistic approach for the robotic manipulation of complex objects toward dry stone construction and use the same hardware and mapping to facilitate autonomous terrain-shaping on a single construction site. Our process is demonstrated with the construction of a freestanding stone wall (10 meters by 1.7 meters by 4 meters) and a permanent retaining wall (65.5 meters by 1.8 meters by 6 meters) that is integrated with robotically contoured terraces (665 square meters). The work illustrates the potential of autonomous heavy construction vehicles to build adaptively with highly irregular, abundant, and sustainable materials that require little to no transportation and preprocessing.

In-Crease: Less Concrete More Paper

Concrete is one of the most used materials after water. Largely owing to this, its environmental impact is substantial, although its embodied carbon per unit volume or mass is low when compared to most alternatives. This, along with the broad availability, good strength, durability and versatility of concrete means that it will remain a material of choice, although more efficient ways of using it must be found. Structurally optimized building components are a means to do this as they can save about 50% material. Unfortunately, however, such elements are presently too expensive to produce owing to them requiring non-standard formwork. It is an objective of digital fabrication to propose solutions to this issue. In this con-text, Digital Casting Systems (DCS) have advanced material control strategies for setting-on-demand in digital concrete processing. Thereby, the formwork pressure is reduced to a minimum, which opens possibilities of rethinking formworks as systems that are dynamically shaping, millimetre thin or weakly supporting the material cast inside. In this paper we present a brief overview of millimetre thin formworks and summarize the first realization of concrete elements that utilizes the mechanics of paper folding to make millimetre thin formworks up to 2.5 meters high. Such formworks could initially be flat packed, erected into shape, and eventually peeled-off and recycled in established material streams. This would reduce waste and transport cost, while offering a surface finish that meets the expectations for exposed concrete surfaces.

Eggshell Pavilion: a reinforced concrete structure fabricated using robotically 3D printed formwork

This paper discusses the design, fabrication, and assembly of the 'Eggshell Pavilion', a reinforced concrete structure fabricated using 3D printed thin shell formwork. Formworks for columns and slabs were printed from recycled plastic using a pellet extruder mounted to a robotic arm. The formworks were cast and demoulded, and the finished elements were assembled into a pavilion, showcasing the architectural potential of 3D printed formwork. The Eggshell Pavilion was designed and fabricated within the scope of a design studio at ETH Zurich. The structure was designed using a fully parametric design workflow that allowed for incorporating changes into the design until the fabrication. The pavilion consists of four columns and floor slabs. Each column and floor slab is reinforced with conventional reinforcing bars. Two different methods are used for casting the columns and floor slabs. The columns are cast using 'Digital casting systems', a method for the digitally controlled casting of fast-hardening concrete. Digital casting reduces the hydrostatic pressure exerted on the formwork to a minimum, thereby enabling the casting of tall structures with thin formwork. The floor slabs are cast with a commercially available concrete mix, as the pressure exerted on the formwork walls is lower than for the columns. In this research, 3D printed formwork is combined with traditional reinforcing, casting, and assembly methods, bringing the technology closer to an industrial application.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41693-023-00090-x.

Digitally fabricated ribbed concrete floor slabs: a sustainable solution for construction

The concrete used in floor slabs accounts for large greenhouse gas emissions in building construction. Solid slabs, often used today, consume much more concrete than ribbed slabs built by pioneer structural engineers like Hennebique, Arcangeli and Nervi. The first part of this paper analyses the evolution of slab systems over the last century and their carbon footprint, highlighting that ribbed slabs have been abandoned mainly for the sake of construction time and cost efficiency. However, highly material-efficient two-way ribbed slabs are essential to reduce the environmental impact of construction. Hence, the second part of this paper discusses how digital fabrication can help to tackle this challenge and presents four concrete floor systems built with digitally fabricated formwork. The digital fabrication technologies employed to produce these slab systems are digital cutting, binder-jetting, polymer extrusion and 3D concrete printing. The presented applications showcase a reduction in concrete use of approximately 50% compared to solid slabs. However, the digitally fabricated complex formworks produced were wasteful and/or labour-intensive. Further developments are required to make the digital processes sustainable and competitive by streamlining the production, using low carbon concrete mixes as well as reusing and recycling the formwork or structurally activating stay-in-place formwork.

Robotic Plaster Spraying: Crafting Surfaces with Adaptive Thin-Layer Printing

Embedded in a long tradition of craftsmanship, inside or outside building surfaces, is often treated with plaster, which plays both functional and ornamental roles. Today, plasterwork is predominantly produced through rationalized, time-, and cost-efficient processes, used for standardized building elements. These processes have also gained interest in the construction robotics field, and while such approaches target the direct automation of standardized plasterwork, they estrange themselves from the inherent qualities of this malleable material that are well known from the past. This research investigates the design potentials of robotic plaster spraying, proposing an adaptive, thin-layer vertical printing method for plasterwork that aims to introduce a digital craft through additive manufacturing. The presented work is an explorative study of a digitally controlled process that can be applied to broaden the design possibilities for the surfaces of building structures. It involves the spraying of multiple thin layers of plaster onto a vertical surface to create volumetric formations or patterns, without the use of any formwork or support structures. This article describes the experimental setup and the initial results of the data collection method involving systematic studies with physical testing, allowing to develop means to predict and visualize the complex-to-simulate material behavior, which might eventually enable to design with the plasticity of this material in a digital design tool.

Impact Printing

This article introduces the concept of Impact Printing, a new additive manufacturing (AM) method that aggregates malleable discrete elements (or soft particles) by a robotic shooting process. The bonding between the soft particles stems from the transformation of kinetic energy, gained during the acceleration phase, into plastic deformation upon impact. Hence, no additional binding material is needed between the soft particles; the cohesion and self-interlocking capacities of the material itself acts as the primary binding agent. Shooting, and consequent impacting, forces can be modulated and result in distinct compaction ratios. By linearly shooting material, we decouple the deposition apparatus from the produced parts and provide flexibility to the deposition process to potentially build in any directions or onto uncontrolled surfaces. Impact Printing produces parts with formal characteristics standing between brick laying-assembly of discrete building blocks-and 3D Printing-computer-controlled depositioning or solidifying of material. It brings forward a novel digital fabrication method and an alternative to the conventional continuous AM process. This article validates the Impact Printing approach with a series of prototypical experiments, conducted with a robotic fabrication setup consisting of a six-axis robotic arm mounted with a material shooting apparatus, that forms, orients, and projects the soft particles. We will explain and demonstrate its principles and define the fabrication parameters, such as shooting force, shooting distance, and the resulting aggregations' characteristics.

A Pedagogy of Digital Materiality: Integrated Design and Robotic Fabrication Projects of the Master of Advanced Studies in Architecture and Digital Fabrication

This paper illustrates the pedagogical approach to teaching computational design and digital fabrication in the Master of Advanced Studies in Architecture and Digital Fabrication. It demonstrates how the introduction of computational design and digital fabrication methods foster a holistic approach to integrate novel material and constructive systems into the design process. Such an integration allows the students to combine digital fabrication techniques with sustainable material processes, taking into account the questions of reversibility, recycling and reuse, and thus designing for a more sustainable construction. In the presented paper, the structure and the curriculum of the MAS programme is introduced and the pedagogical approach of the Integrated Design and Robotic Fabrication Project is demonstrated through four case studies, highlighting their respective teaching strategies in combination with the learning experiences of the students.

Design and structural analysis of complex timber structures with glued T-joint connections for robotic assembly

Combining computation and robotic fabrication and assembly creates rationale for new types of design and construction methods which are not bound to constraints of standardization and allows structurally informed differentiation. This research presents methods for designing and analysis of structural behavior for novel types of timber structures made of simple elements which are suitable for robotic assembly. Specifically, structures derived from Reciprocal Frames built with linear timber elements and connected with glued butt T-joints were of interest due to their applicability in integrated robotic fabrication and assembly processes. So far, little has been known about the complexity of their structural behavior and their potential for load-bearing application in construction. In response, this research established a corresponding structural analysis method for such structures and specifically the adhesive-based T-joint connections. Furthermore, this analysis method has been implemented as a computational tool integrated with algorithmic design modeling methods, which supports an architect or an engineer in exploring the potential designs based on immediate structural feedback. Finally, these tools were employed to conduct case studies which show that the structural behavior of the discussed structures is highly complex, and slight geometric modification allows to significantly improve the load-bearing capacity.

Digital Concrete: Opportunities and Challenges

Digital fabrication has been termed the “third industrial revolution” in recent years, and promises to revolutionize the construction industry with the potential of freeform architecture, less material waste, reduced construction costs, and increased worker safety. Digital fabrication techniques and cementitious materials have only intersected in a significant way within recent years. In this letter, we review the methods of digital fabrication with concrete, including 3D printing, under the encompassing term “digital concrete”, identifying major challenges for concrete technology within this field. We additionally provide an analysis of layered extrusion, the most popular digital fabrication technique in concrete technology, identifying the importance of hydration control in its implementation.

[Variations in interleukin-2 and interleukin-6 due to surgical trauma in cancer patients]

Inflammatory response after surgical trauma, which is necessary for infection control and tissue repairing, can actually produce some cytokines suppressive of the antitumoral immunity response. In this study the authors evaluate pre- and post-operative IL-2 (antitumor response activator) and IL-6 (lymphocytic response inhibitor and tumor growth factor) levels in 26 cancer patients undergoing resective surgery. Analysis of the results showed a significative IL-6 increase and a tendency to IL-2 decrease in the post-operative period. It is thus confirmed, even on the basis of the cytokines, the meaningful immunosuppressive effect of the surgical trauma on neoplastic growth control.

Immune effects of preoperative immunotherapy with high-dose subcutaneous interleukin-2 versus neuroimmunotherapy with low-dose interleukin-2 plus the neurohormone melatonin in gastrointestinal tract tumor patients

Surgery-induced immunosuppression could influence tumor/host interactions in surgically treated cancer patients. Previous studies have shown that high-dose IL-2 preoperative therapy may neutralize surgery-induced lymphocytopenia. Moreover, experimental studies have demonstrated that the immunomodulating neurohormone melatonin (MLT) may amplify IL-2 activity and reduce its dose required to activate the immune system. On this basis, we have compared the immune effects of presurgical therapy with high-dose IL-2 with respect to those obtained with preoperative neuroimmunotherapy consisting of low-dose IL-2 plus MLT. The study included 30 patients with gastrointestinal tract tumors, who were randomized to undergo surgery alone, or surgery plus a preoperative biotherapy with high-dose IL-2 (18 million IU/day subcutaneously for 3 days) or low-dose IL-2 (6 million IU/day subcutaneously for 5 days) plus MLT (40 mg/day orally). Patients underwent surgery within 36 hours from IL-2 interruption. Both IL-2 plus MLT were able to prevent surgery-induced lymphocytopenia. However, mean number of lymphocytes, T lymphocytes and T helper lymphocytes observed on day 1 of postoperative period was significantly higher in patients treated with IL-2 plus MLT than in those receiving IL-2 alone. Moreover, toxicity was less in patients treated with IL-2 and MLT. This biological study shows that both immunotherapy with high-dose IL-2 or neuroimmunotherapy with low-dose IL-2 plus MLT preoperatively are tolerated biotherapies, capable of neutralizing surgery-induced lymphocytopenia in cancer patients. Moreover, the study would suggest that the neuroimmunotherapy may induce a more rapid effect on postoperative immune changes with respect to IL-2 alone.